Dell Studio 1558 screen problem

i have dell studio 1558 its about 4 month.About few week ago the lower part of screen start showing some red lines now the red line become a thick black line.guys please tell me how to correct this problem??

Have you tried plugging your laptop to an external monitor to see if it does the same thing if it does it could
Mean you have trouble with your graphics chip so please check this out first then we can go from here.